Flux gate compasses are known and include a pair of coils wound about a saturable magnetic core. Two or more coils are provided in orthogonal disposition on a platform which is gimballed to remain in substantially horizontal orientation. The output signals derived from the coils are proportional to the sine and cosine, respectively, of the heading. The output signals can be represented by K sin .theta. and K cos .theta., where .theta. is the angle of the coil axis with respect to the horizontal component of the earth's magnetic field, that is, the heading; and K is a parameter being measured, such as voltage, current, or frequency. In actual practice, the output signals are of the form K sin .theta.+C.sub.1 and K cos .theta.+C.sub.2, where C.sub.1 and C.sub.2 are error terms occasioned by changes or variations due to temperature, aging of system components, mismatch of component values, and the like. Conventionally, potentiometer adjustments are provided in an effort to maintain the terms C.sub.1 and C.sub.2 near zero. It is an object of this invention to provide a solid state compass in which the error terms are automatically cancelled.
It is also an object of this invention to provide a gimballed platform which is relatively small to increase the resonant frequency of the gimballed structure, thereby to improve overall compass performance, and also to provide a compass structure which can be readily miniaturized, as is desirable for many applications.
As a further object, the invention provides a single electronic subsystem which is multiplexed for use with each flux gate of the compass, with all power and signal communication being by way of a single pair of conductors.